Recently developed electrophotographic photoreceptors include those comprising a conductive support having thereon a photoconductive layer mainly comprising amorphous silicon. The photoreceptors of this type are excellent in mechanical strength, panchromatic properties, and sensitivity to long wavelength light as compared with those having a photoconductive layer comprising other inorganic photoconductive materials, e.g., Se, tri-Se, ZnO or CdS, or various organic photoconductive materials. However, they cause image deletion when left to stand in the atmosphere, particularly under a high temperature and high humidity condition. Besides, the surface of the photoconductive layer tends to receive scratches due to contact with a toner cleaning blade or a paper stripping click during electrophotographic processing, to cause white streaks on an image of copies.
In order to improve scratch resistance of a photosensitive layer, it has been proposed to provide a surface layer having a composition, such as SiN.sub.x, SiO.sub.x, and SiC.sub.x, which does not impair hardness of a photosensitive layer mainly comprising silicon. The above disadvantage can be removed by providing such a surface layer. It has also been proposed to provide a surface layer comprising amorphous carbon for the purpose of improving endurance against repeated use under a high temperature and high humidity condition as disclosed in JP-A-61-250655 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
However, electrophotographic photoreceptors having a surface layer comprising SiN.sub.x, SiO.sub.x, SiC.sub.x, etc. turned out to cause image deletion on repeated use in a high temperature and high humidity condition, proving practically useless. Further, those having a surface layer comprising amorphous carbon turned out to induce reduction of surface potential.